Tryptamine has been applied to the determination of poly[methylene(polyphenyl isocyanate)](PMPPI) in air. Tryptamine acts as a derivatising agent and calibration standard when quantifying PMPPI samples. Tryptamine-derivatised airborne PMPPI is analysed using gel-permeation or normal-phase high-performance liquid chromatography with fluorescence detection. As tryptamine is both fluorescence and amperometric oxidation active, confirmation of the presence of PMPPI is currently conducted amperometrically.